If you've been scrolling TikTok lately, you might have noticed something strange about certain singing videos. The melody sounds familiar, but the lyrics don't quite match.

Creators are singing the lyrics of one song over the melody of another—often two songs that were never meant to meet. Sometimes the result is oddly satisfying. Other times, it sounds completely wrong. Either way, it's hard not to watch until the end.

You've just stumbled onto one of the newest singing trends gradually taking over social media—the Mashup Singing Challenge.

On TikTok, you'll see friends challenging each other to sing ridiculous song combinations, using such combinations as pranks, or solo creators singing confidently a song that sounds just a little off.

If you've been wondering what this challenge is about, why it's suddenly everywhere, and how people are making these mashups to post on TikTok, this guide will walk you through it.